Various techniques and devices increase the firing rate of a semi-automatic firearm. Bump firing is a technique of firing a semi-automatic firearm using the recoil energy from firing the weapon to rapid-fire faster than what an operator could achieve by repeated finger pulls.
Operators may bump fire a semi-automatic firearm without the use of tools, accessories, or alterations to the weapon, but such freehand techniques are difficult to master. To execute a freehand technique, the operator generally holds the semi-automatic firearm away from his or her body in order to allow the weapon to recoil after firing. One freehand technique has the operator hold a trigger hand in a rigid position with a trigger finger just in front of the trigger while placing a forend hand (i.e., the other hand) on a hand guard of the weapon. The hand guard generally covers the barrel of the semi-automatic firearm, which is forward of the trigger. Using the forend hand to push the hand guard forward, while maintaining the trigger hand in the rigid position, the semi-automatic firearm shifts forward relative to the trigger hand This forward movement causes the trigger to engage the trigger finger, which if held firmly in the rigid position will discharge the semi-automatic firearm. Recoil from the discharge of a bullet pushes the semi-automatic firearm rearwards away from the trigger finger, allowing the trigger to re-set. If the operator maintains a forward force on the hand guard while keeping the trigger hand stationary in the rigid position (i.e., pulling the forend hand away from the trigger hand), the operator will be able to once again push the hand guard forward after the recoil energy dissipates, which once again discharges the weapon. By continuously maintaining the forward force on the hand guard with the trigger hand in the rigid position, the weapon will discharge in a rapid-fire succession that is generally faster than what the operator can achieve with repeated finger pulls. Not all operators that attempt this technique are successful or consistently successful.